WO2016174320A1 - Combustion engine for a motor vehicle, comprising a system for varying the compression ratio - Google Patents

Abstract

The invention relates to an internal combustion engine (10) for a motor vehicle, comprising: a crankshaft (15) that can rotate a pulley (21); a system (11) for varying a compression ratio of the engine (10), including at least one eccentric part mounted on at least one crank pin; and a control system (29), a control shaft (32) equipped with a control pinion (33), and a movement transmission device installed between the control pinion (33) and a transfer pinion (35) mounted on a transfer shaft (36) that is mechanically connected to the eccentric part. According to the invention, the transfer shaft (36) and the transfer pinion (35) are assembled to the crankshaft (15), and the external diameter (D1) of the transfer pinion (35) is smaller than an internal diameter (D2) of a securing element (51).

Description

 INTERNAL COMBUSTION ENGINE OF A MOTOR VEHICLE WITH A SYSTEM OF VARIATION IN THE RATE OF COMPRESSION

The present invention relates to an internal combustion engine of a motor vehicle equipped with a compression ratio variation system. The document EP14163870.0 teaches the realization of a compression ratio variation system depending on the operating conditions of the engine. This system comprises for this purpose a set of eccentric parts mounted on the crankshaft crank pins so as to cooperate each with a connecting rod end. In addition, a system for controlling the position of the eccentric members includes a housing, a control shaft with a drive gear, and a motion transmission device installed between the drive gear and a transfer gear mounted on a Transfer shaft mechanically linked to eccentric parts.

The invention aims to facilitate the mounting of the control system by proposing an internal combustion engine of a motor vehicle comprising:

a crankshaft capable of rotating a pulley,

 a system for varying a compression ratio of said engine comprising at least one eccentric part mounted on at least one crankpin, and

 a control system comprising a housing, a control shaft provided with a drive gear, and a motion transmission device installed between said drive gear and a transfer gear mounted on a transfer shaft mechanically connected to said workpiece. eccentric,

characterized in that said transfer shaft and said corresponding transfer pinion are assembled on said crankshaft, and in that an outer diameter of said transfer pinion is less than an inner diameter of a fastener element capable of securing a fastener between said crankshaft and a part rotatably connected with said pulley.

The invention thus facilitates the assembly of the control system by allowing an assembly of the transfer shaft with its pinion on the crankshaft prior to the installation of the control system on the front part of the crankshaft.

According to one embodiment, said motion transmission device comprises at least one intermediate gear meshing with said control pinion and on the other hand with a pinion satellite, said pinion stellite meshing further with said pinion transfer.

In one embodiment, an axial holding plate of said transfer shaft is mounted against a bottom of the pulley. The axial retention of the shaft is thus achieved independently of the housing.

In one embodiment, said holding plate has an opening greater than the outer diameter of said transfer pinion. Thus, the holding plate can be mounted against the inner face of the pulley while the transfer pinion and the corresponding shaft are already assembled on the crankshaft. In one embodiment, said transfer shaft has an end mounted in a hollow portion of said crankshaft and another end supported in a hollow portion of said control shaft. This ensures proper alignment between the drive gear and the transfer gear.

According to one embodiment, a lubrication circuit comprises a duct formed in said transfer shaft for taking lubricating liquid from said engine and conveying said lubricating liquid to said housing.

In one embodiment, said duct is configured to take lubricating liquid from said engine at a front bearing of said crankshaft.

[001 1] In one embodiment, said lubrication circuit is configured to circulate the lubricating liquid from an end of the hollow control shaft to the bearings of the intermediate gears and satellites.

In one embodiment, said lubrication circuit comprises openings in a bottom of the pulley adapted to allow a return of the lubricating liquid to said engine. In one embodiment, each hole is positioned between two adjacent gears rotating in opposite directions so that said gears form a pump for pumping the lubricating liquid towards the crankshaft.

The invention also relates to an internal combustion engine of a motor vehicle comprising:

a crankshaft capable of rotating a pulley, a system for varying a compression ratio of said engine comprising at least one eccentric part mounted on at least one crankpin, and

 a control system comprising a housing, a control shaft provided with a drive gear, and a motion transmission device installed between said drive gear and a transfer gear mounted on a transfer shaft mechanically connected to said workpiece. eccentric,

characterized in that said transfer shaft has an end mounted in a hollow portion of said crankshaft and another end supported in a hollow portion of said drive shaft. The invention further relates to an internal combustion engine of a motor vehicle comprising:

 a crankshaft capable of rotating a pulley,

 a system for varying a compression ratio of said engine comprising at least one eccentric part mounted on at least one crankpin, and

a control system comprising a housing, a control shaft provided with a drive gear, and a motion transmission device installed between said drive gear and a transfer gear mounted on a transfer shaft mechanically connected to said workpiece. eccentric,

characterized in that a lubrication circuit has a conduit in said transfer shaft for collecting lubricating liquid from the engine and conveying the lubricating liquid to said housing.

The invention will be better understood on reading the description which follows and the examination of the figures that accompany it. These figures are given for illustrative but not limiting of the invention. Figure 1 is a perspective view illustrating a section of an internal combustion engine equipped with a compression ratio variation system according to the present invention;

Figure 2 is a perspective view along a longitudinal section of a compression rate variation system of the engine according to the present invention; Figure 3 is an exploded perspective view of a control system of the engine compression ratio variation system according to the present invention; Figure 4 shows perspective views illustrating the mounting of the pulley on the front portion of the crankshaft and the establishment of the axial holding plate of the transfer shaft;

Figure 5 is a perspective view of the axial holding plate of the transfer shaft according to the present invention;

Figure 6 is a front view of the compression ratio variation system according to the present invention without the hood.

Identical elements, similar, or the like, retain the same reference from one figure to another. [0024] Figure 1 shows a partial perspective view of an internal combustion engine 10 according to the present invention. This engine 10 comprises a system 1 1 for varying the compression ratio to operate the engine 10 at a high compression ratio under low load conditions to improve its performance. Under high load operating conditions, the compression ratio can be decreased to avoid jolts.

More specifically, the motor 10 comprises a housing 12 supporting a crankshaft 15 via bearings. The crankshaft 15 has an axis X and is rotatable relative to the housing 12 about this axis X. The crankshaft 15 comprises a crank pin 16, a central portion 17, and a flange 18 positioned axially between the central portion 17 and the crank pin 16. It should be noted that in FIG. 1, the left part corresponds to the front side of the engine 10.

The central portion 17 of the crankshaft 15 projecting from the housing 12 on the front side of the engine 10 is rotatably connected to a pulley 21. On the opposite rear side, a flywheel (not shown) is rotatably connected to the crankshaft 15. Although FIG. 1 shows a single-cylinder engine 10 to facilitate readability, the engine 10 has a priori several cylinders, typically three or four cylinders.

The motor 10 comprises an eccentric part 22 rotatably mounted on the crankpin 16. The eccentric part 22 has an eccentric outer face 221 relative to the inner face cooperating with a large end of a connecting rod 25. The eccentric piece 22 also has two gears 222 positioned on the side and other than the eccentric outer face 221. The rod 25 furthermore has a small end connected in rotation with a piston 26 of the engine 10.

The eccentric part 22 belongs to the system 1 1 of variation of the compression ratio which further comprises a control system 29 of the angular position of the eccentric part 22. This control system 29 is positioned inside of a hollow delimited by the pulley 21. As can be seen in FIGS. 2 and 3, the control system 29 comprises a housing 31, a control shaft 32 provided with a control pinion 33, and a motion transmission device 34 mounted between the control pinion 33 and a transfer pinion 35. The transfer pinion 35 is mounted on a transfer shaft 36 mechanically connected to the eccentric member 22. For this purpose, the transfer shaft 36 comprises a second pinion 35 'meshing with a toothed wheel of the eccentric part 22.

Preferably, the transfer shaft 36 has an end mounted in a hollow portion of the crankshaft 15 and another end supported in a hollow portion of the control shaft 32. This ensures a correct alignment between the drive gear 33 and the transfer pinion 35.

As shown in Figure 3, the motion transmission device 34 comprises a set of intermediate gears 41 meshing each on the one hand with the control pinion 33 and on the other hand with a pinion gear 42 inverting the sense of rotation. Each planet pinion 42 also meshes with the transfer pinion 35.

Each of the intermediate gears 41 and satellites 42 is rotatably mounted on a shaft 43 fixed to the housing 31 by means of screws 44. Preferably, for more compactness, the gears 41, 42 are mounted in rounded recesses of the housing 31 of complementary shape. Alternatively, the movement transmission device 34 may include a belt device as described in EP14163870.0.

The control shaft 32 is mounted inside a tubular sleeve 47 of a cover 48 by means of a bearing 50. The cover 48 is intended to close the housing 31. A seal 49 closes the lubrication circuit 71 described in more detail below. The angular position of the eccentric parts 22 is controlled by the angular position of the control shaft 32 so as to be able to vary the rate of compression of the heat engine 10. For this purpose, the control shaft 32 may be actuated for example by means of a wheel and worm gear (not shown), or any other means of displacement adapted to the application.

The transfer pinion 35 and the transfer shaft 36 are assembled on the crankshaft 15. As can be seen in FIG. 2, an external diameter D1 of the transfer pinion 35 is smaller than the internal diameter D2 of a fastener element. 51, such as a nut, adapted to ensure a fixing between the crankshaft 15 and a part 52 intended to be linked in rotation with the pulley 21. The outer diameter D3 of a flange 53 of the transfer shaft 36 bearing against an end face of the central portion 17 of the crankshaft is also smaller than the internal diameter D2 of the nut 51. This facilitates the assembly of the control system 29 by allowing a prior connection between the transfer pinion 35 and the transfer shaft 36 on the crankshaft 15.

In addition, a plate 61 for axially holding the shaft 36 is mounted against the bottom of the pulley 21. The flange 53 bears against one edge of the holding plate 61. The maintenance of the shaft 36 is thus achieved independently of the housing 31. For this purpose, the retaining plate 61 has an opening 62 greater than the external diameter D1 of the transfer gear 35. The holding plate 61 can thus be mounted against the bottom of the pulley 21 while the transfer gear 35 and the corresponding shaft 36 are already assembled on the crankshaft 15 (see FIG. In the present case, as shown in FIG. 5, the plate 61 generally has the shape of a disc provided with an opening 62 in the form of a half-disc having an indentation 63 in the central part so as to marry. the outer periphery of the shaft 36. The plate 61 has holes 64, some of which allow the passage of fastening means 65 such as screws (see Figure 2), and others allow the passage of tubes 66 (cf. Figures 2 and 3) for the return of the lubricating liquid.

Furthermore, a lubrication circuit 71 visible in Figure 2 comprises a conduit 72 formed in the transfer shaft 36 for taking lubricating liquid from the engine 10, in this case the oil, and route it up to to the housing 31. The conduit 72 is configured to draw oil from the engine 10 at a front bearing of the crankshaft 15 and convey it to an end of the hollow control shaft 32, to be able to circulate the oil until Bearings of intermediate gears 41 and planet gears 42. The flow direction of the oil inside circuit 71 is indicated by arrows F. The lubrication circuit 71 has openings 74 formed in the bottom of the pulley 21 adapted to allow a return of the oil to the engine 10. These openings 74 receive the aforementioned tubes 66. As illustrated in FIG. 6, each opening 74 is advantageously positioned between two adjacent gears 41, 42 rotating in opposite directions so that said gears 41, 42 form an oil pump for pumping the oil towards the crankshaft 15.

Of course, for a motor comprising a plurality of cylinders, the crankshaft 15 may comprise other transfer shafts positioned within an axial bore formed in the trunnions located in the extension of the bore made in the portion. central 17, as well as corresponding transfer gears meshing with the gears eccentric parts 22 mounted on the crank pins to transmit the kinematics to all the eccentric parts 22 of the motor 10.

Claims

An internal combustion engine (10) of a motor vehicle comprising:  a crankshaft (15) capable of rotating a pulley (21),  a system (1 1) for varying a compression ratio of said motor (10) comprising at least one eccentric part (22) mounted on at least one crankpin (16) of the crankshaft, and  a control system (29) comprising a housing (31), a control shaft (32) provided with a control pinion (33), and a motion transmission device (34) installed between said control gear ( 33) and a transfer pinion (35) mounted on a transfer shaft (36) mechanically connected to said eccentric member, characterized in that said transfer shaft (36) and said corresponding transfer pinion (35) are assembled on said crankshaft (15), and in that an outer diameter (D1) of said transfer gear (35) is smaller than an inner diameter (D2) of a fastening element (51) adapted to ensure a connection between said crankshaft ( 15) and a part (52) rotatably connected to said pulley (21). 2. Motor according to claim 1, characterized in that said motion transmission device (34) comprises at least one intermediate gear (41) meshing on the one hand with said control gear (33) and on the other hand with a satellite gear (42), said stellite gear (42) meshing further with said transfer pinion (35). 3. Motor according to claim 1 or 2, characterized in that a plate (61) for axially holding said transfer shaft (36) is mounted against a bottom of the pulley (21). 4. Motor according to claim 3, characterized in that said plate (61) has an opening (61) greater than the outer diameter (D1) of said transfer pinion (35). 5. Motor according to any one of claims 1 to 4, characterized in that said transfer shaft (36) has an end mounted in a hollow portion of said crankshaft (15) and another end supported in a hollow portion of said shaft. control (32). 6. Engine according to any one of claims 1 to 5, characterized in that a lubrication circuit (71) comprises a conduit (72) formed in said transfer shaft (36) for taking lubricating liquid from the engine (10). ) and convey the lubricating liquid to said housing (31). 7. Engine according to claim 6, characterized in that said duct (72) is configured to take lubricating liquid from the engine (10) at a front bearing of said crankshaft (15). 8. Engine according to claim 2 taken in combination with claim 6 or 7, characterized in that said lubrication circuit (71) is configured to circulate the lubricating liquid from one end of the hollow control shaft (32) to to bearings of the intermediate gears (41) and satellites (42). 9. Motor according to any one of claims 1 to 8, characterized in that said lubrication circuit (71) comprises openings in a bottom of the pulley (21) adapted to allow a return of the lubricating liquid to said engine ( 10). 10. Motor according to any one of claims 1 to 9, characterized in that each hole is positioned between two adjacent gears (41, 42) rotating in opposite directions so that said gears (41, 42) form a pump for pumping the lubricating liquid towards the crankshaft (15).